Some would even say to keep your bot Java 5 compatible. This means compiling with -target 1.5 -source 1.5 and avoiding features introduced in later versions of Java. The RoboRumble client places no restrictions on the version of Java used to run matches, and someone might run your robot with Java 5, producing invalid battle results.

Try out your just-packaged bot before letting it loose in the rumble.

If your robot is worse than MyFirstRobot, don't enter it.

Publishing the JAR

You will need to upload your robot's JAR on a website that can store arbitrary files, giving you an URL with which others can download your robot. Keep in mind the following:

The link must be a direct link. When the link is clicked, the JAR must immediately begin downloading, without any intermediate page.

The link should not break. You should upload your JAR to a reliable file storage service. Random "free online hosting" services are definitely out. Broken links generally will not cause data loss, as all JARs entered into the rumble are backed up on Rednaxela's server; they are just annoying to fix.

Google Drive, Dropbox, GitHub, OneDrive etc are not good options too. They might last longer than your own web host. But the prone to change file accessing API or worse require a human interaction to download a file. On 2017/09/07 we had to clean up a lot of Dropbox, GitHub, Google Drive links.

If you are desperate use above big brother hostings. Below the known ways to modify their links to a workable ones.